Background: Disability resulting from stroke and traumatic brain injury represent the main cause of long term disability among adults. There are no universally accepted treatments available for the treatment of this condition and the financial, personal, familiar and social cost of this disability cannot be underestimated. Preliminary data from different laboratories has shown that it is possible to modulate plastic processes in the lesioned brain by pharmacological, brain stimulation and somatosensory stimulation techniques. The purpose of this Z01 is to characterize the most promising techniques to improve cortical plasticity in these patients in order to enhance functional recovery. Findings this year: This year we studied motor cortical function associated with post stroke epilepsy, an area that has not been explored before in detail, finding important correlates between changes in motor cortical excitability and this condition. We expanded our work on the usefulness of somatosensory stimulation on motor function after stroke and studied in particular function in the contralesional primary motor cortex after this intervention. One of our fellows was honored by describing the development of neurorehabilitation as a subspecialty in the journal Neurology. We continued work to better understand the physiology of brain-computer interfaces in patients with paralysis secondary to stroke and other disorders. We characterized the effects of action observation on physical training after stroke, noting its benefits. We also characterized an important set of interactions between somatosensory stimulation of the paretic hand after stroke and changes in interhemispheric interactions. We advanced our understanding of the interactions between interhemispheric interactions and intracortical inhibitory gabaergic circuits during movement preparation after stroke. In collaboration with extramural investigators, we proceeded to study further the influence of somatosensory stimulation on motor function when administered in the weeks following stroke. Our future plans include advancing our understanding of the mechanisms by which each of these different stimulation techniques including somatosensory stimulation, cortical stimulation and brain computer interfaces contribute to recovery of motor functions after brain lesions. Some of this work will be focused in the upcoming year on traumatic brain injury, predominantly mild to moderate. Additionally, we will try to determine the optimal parameters of stimulation and techniques to enhance the beneficial effects of this intervention on neurorehabilitative treatments. Implications: The significance of this project is that it can lead to a better understanding of the mechanisms underlying rehabilitative processes and to the development of more effective interventions to improve neurological outcome after stroke and traumatic brain injury using brain stimulation techniques.